<?php
if(isset($_POST['comment'])) {
  $comment = trim($_POST['comment']);
  echo $comment  ;
}
?>
<!---
  <script>alert('You are hacked !!')</script>
  <script>window.location="http://google.com"</script>
-->
<form name="testData" action="" method="post">
  Please enter your comment below:<br>
  <textarea name="comment"></textarea><br>
  <input type="submit">
</form>
